I'm pretty sure TheWatcher, (BrokenLens' anticheat system) does try to detect these apps and modifications
No i used an app it didnt detect it i feel very bad for hacking if you wanna know the app its called toolbox for minecraft i want it removed or blocked bet of people are getting away with it.
Not necessarily hacking mods, there are some addons that require blocklauncher or toolbox in order to download them. For example, I really wanted to download a worldedit addon, but it needed blocklauncher. I didn’t end up downloading it because I didn’t want blocklauncher, but other people would probably download it if they wanted
actually, minecraft servers can only have server-side anti cheat plugins not client-sided, so it cannot detect 3rd party apps.